// GenericsNote: Converted.
/*
 *  Copyright 2001-2004 The Apache Software Foundation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.apache.commons.collections15;

/**
 * Defines a functor interface implemented by classes that transform one object
 * into another.
 * <p/>
 * A <code>Transformer</code> converts the input object to the output object.
 * The input object should be left unchanged. Transformers are typically used
 * for type conversions, or extracting data from an object.
 * <p/>
 * Standard implementations of common transformers are provided by
 * {@link TransformerUtils}. These include method invokation, returning a
 * constant, cloning and returning the string value.
 *
 * @author James Strachan
 * @author Matt Hall, John Watkinson, Stephen Colebourne
 * @version $Revision: 1.1 $ $Date: 2005/10/11 17:05:19 $
 * @since Commons Collections 1.0
 */
public interface Transformer<I, O> {

	/**
	 * Transforms the input object (leaving it unchanged) into some output
	 * object.
	 *
	 * @param input
	 *            the object to be transformed, should be left unchanged
	 * @return a transformed object
	 * @throws ClassCastException
	 *             (runtime) if the input is the wrong class
	 * @throws IllegalArgumentException
	 *             (runtime) if the input is invalid
	 */
	public O transform(I input);

}
